What is a network?

A network is a group of peripherals, computers, servers, network devices, mainframes, and other devices that are connected to allow electronic communication, and data and resource sharing. The computer network connects the devices either by using cables or wireless fidelity to transmit, share, or exchange both resources and data.

What is meant by network recovery?

The process of recovering and restoring the working operation on the computer network is known as network recovery.  It helps the network administrator to restore and regain the operation on the network after a network failure caused due to disconnection, network error, hardware failure, or any other event. The reasons for the network failure are as follows:

• Network hardware problems where devices such as switches and routers stop working.
• Internet connectivity problems arise when the network goes offline after the Internet, satellite or leased line connection is disrupted or lost.
• Network attacks which happen when the network is unavailable due to attacks such as Denial of Service(DoS), Distributed Denial of Service (DDoS), etc.

Network recovery plan

Generally, the network disaster recovery plan is in a formal document, which is created by the network management staff and network administrator. Based on the requirements of the organization and network, the procedure and plan for recovery are included. These procedures and plans are included to recover the following:

• Wide-Area Network (WAN)
• Local-Area Network (LAN)
• Wireless network
• Computer systems
• Servers

The network recovery includes routers, firewalls, and switches recovery. The disasters could be either physical or natural such as fire, flooding, or virtual disasters like hackers or viruses attacks. The purpose of the recovery plan is to minimize the interrupts on normal operations, minimize the economic impact of interruption, provide rapid and smooth restoration of service, limit the extent of damage and disruption, and establish an alternative means of operation in advance.

What is meant by network performance?

Network performance is the review and analysis of network statistics. It defines the service quality provided by the computer network. The network performance level is defined by measuring the quantitative and qualitative processes. Network performance helps the administrator to measure, review, and improve the network service.

Network performance monitoring

The process of monitoring, optimizing, visualizing, reporting, and troubleshooting on the availability of the network (as per user experience) is known as Network Performance Monitoring (NPM). The working of NPM is to collect the data from different sources like Simple Network Management Protocol (SNMP), packets, and flow data. NPM solutions are available as hardware, cloud, and virtual software. The user has proper visibility across the multi-cloud or hybrid environment. The NPM tools can be utilized in different types of telemetry including,

• Packet data carry the data across the network.
• Device metrics like SNMP, Windows Management Instrumentation (WMI), command-line interface (CLI), etc.
• Network flow data like jFlow, NetFlow, etc.

Characteristics of network performance

The measure of service quality of a network as experienced by the user is referred to as network performance. Generally, network performance is measured using different methods. To ensure the optimized performance of the network the following characteristics are used. The performance of the network is measured by the following,

Bandwidth

Bandwidth is used to determine how fast the webserver uploads the requested data. It is the measure of the amount of information or data which is transmitted over a fixed period of time. In digital devices, bandwidth is measured either in bytes per second (Bps) or bits per second (bps); whereas, in analog devices, it is measured either in Hertz (Hz) or cycle per second.

Bandwidth in Hertz: A frequency range in composite signal or a frequency range which a channel could pass.

Bandwidth in bits per second: The number of bits per second which a link, channel, or network could transmit.

Throughput

Throughput is the number of messages which are transmitted successfully per unit time. Throughput can be controlled by hardware limitation, signal-to-noise ratio, and bandwidth. Compared to actual throughput obtained in daily consumption, the network’s maximum throughput is consequently higher. The potential measurement of the link is known as bandwidth and the actual measurement of how fast the data can be sent is known as throughput.

Throughput is measured by calculating the amount of data transferred between different locations during a specific period of time and results in units of bits per second (bps), which is evolved to bytes per second(Bps), kilobytes per second (KBps), gigabytes per second (KBps), and megabytes per second (KBps). Throughput is affected by different factors like end-user behavior, power of the device components, and analog physical medium.

Latency

Latency refers to the time taken by the message to reach its destination. In other words, Latency is the time needed to send the packet over the internet. In a network connection, when the delay is small then it is known as low-latency-network and high delay is known as high-latency-network. During network communication, high latency creates a bottleneck that prevents the data from filling the network pipes thus it decreases the effective bandwidth. Depending on the source of delay, the impact of latency on the network bandwidth can be either persistent (constant) or temporary (last for a few seconds). The formula to calculate latency is,

$\mathrm{Latenc}y=\mathrm{Queuing} \mathrm{time}+\mathrm{Propagation} \mathrm{time}+\mathrm{Processing} \mathrm{delay}+\mathrm{Transmission} \mathrm{time}$

Propagation time: The time required by the bit to travel from the source location to the destination. It is calculated by the ratio between distance and speed. The formula to calculate propagation time is mentioned below.

$\mathrm{Propagation} \mathrm{time}=\frac{\mathrm{Distance}}{\mathrm{Propagation} \mathrm{speed}}$

Queuing time: The total time taken by the packet to wait in the router is called queuing time. Packets cannot be transmitted immediately, as the wire gets busy frequently.

Transmission time:  The time taken to send the signal down the transmission line is known as transmission time. Depending upon the bandwidth of a channel and message size, the transmission time for a message is calculated. The formula for calculating transmission time is mentioned below.

$\mathrm{Transmission} \mathrm{time}=\frac{\mathrm{Message} \mathrm{size}}{\mathrm{Bandwidth}}$

Processing Delay: Processing delay is the delay that is based on how long it takes the router to figure out where to send the packet. Once the router finds where to send the data, it queues the packets for transmission. The cost is predominantly based on the protocol’s complexity.    

Jitter

Jitter is considered as the problem when multiple data packets face delays in the network and the data at the receiver application is time-sensitive. Technically, it is packet delay variance. Jitter can be measured in milliseconds(ms). It is an interference in the normal order of sending the data packets.

Jitter can occur due to some factors (where the factors are the same which cause delay). Jitter will not affect all the network traffic in the same manner. The major cause of jitter is electromagnetic interference and crosstalk between the signals.

Context and Applications

This topic is important for postgraduate and undergraduate courses, particularly for,

• Bachelors in computer science engineering.
• Associate of science in computer science.

Practice Problems

Question 1: ___ is the process of restoring and recovering the working operation.

a) Network recovery

b) Monitoring

c) Network performance

d) None of the above

Answer: Option a is correct.

Explanation: Network recovery is a process, which restores and recovers the working operation. The network administrator uses network recovery to restore and regain the operation on a network after a failure.

Question 2: What is NPM?

a) Network Plan Monitoring

b) Network Performance Monitoring

c) National Performance Monitoring

d) Network Performance Managing

Answer: Option b is correct.

Explanation: Network performance monitoring is the full form of NPM. This is to monitor, optimize, visualize, and report the availability of the network as per user experience.

Question 3: Select the characteristic which does not belong to network performance.

a) Bandwidth

b) Latency

c) Throughput

d) Speed

Answer: Option d is correct.

Explanation: To ensure the performance of the network the characteristics like bandwidth, latency, jitter, and throughput are used to measure the performance of the network.

Question 4: NPM solutions are available in the form ___.

a) Hardware

b) Virtual software

c) Cloud

d) All the above

Answer: Option d is correct.

Explanation: NPM solutions are available in hardware, cloud, and virtual software, so the user can have exact visibility over the multi-cloud or hybrid environment.

Question 5: What is the correct formula for transmission time?

$$\begin{gathered} \mathrm{a}) \frac{\mathrm{Message} \mathrm{size}}{\mathrm{Bandwidth}} \\ \mathrm{b}) \frac{\mathrm{Distance}}{\mathrm{Propagation} \mathrm{speed}} \\ \mathrm{c}) \frac{\mathrm{Message} \mathrm{size}}{\mathrm{Distance}} \\ \mathrm{d}) \frac{\mathrm{Distance}}{\mathrm{Bandwidth}} \end{gathered}$$

Answer: Option a is correct.

Explanation: Transmission time is the time taken to send a signal to the transmission line. Transmission time for the message depends on the channel bandwidth and message size. The correct formula to calculate transmission time is,

$\mathrm{Transmission} \mathrm{time}=\frac{\mathrm{Message} \mathrm{size}}{\mathrm{Bandwidth}}$